NEED HELP WITH A,B & C

A company received an invoice for $2540.23 dated March 15 with terms 4/10, 1/30, n/60. (a) If the invoice is paid on March 20, how much is to be paid? (b) If the invoice is paid on April 10, how much is to be paid? (c) If the invoice is paid on May 11, how much is to be paid? (a) The amount to be paid on March 20 is 5 (Round the final answer to the nearest cent as needed. Round all intermediate values to six decimal places as needed.)